Getting $USER inside shell script when running with sudo?

Question

How do I get the correct $USER if I run a shell script with sudo ?

I run them as postinstall scripts in a Mac install package, where they are being sudo-ed automatically, but I need to do stuff with the username.

$HOME is correct, though. The inelegant method would be to extract the name from the home path, but I wonder if there is a natural way to do this.

I can't influence the way the scripts are being called, as it's an automatic call inside the installer.

score 44 · Accepted Answer · edited Apr 06 '14 at 23:20

44

On my system the variable $SUDO_USER is set to the caller's user name.

You shouldn't extract the username from the ${HOME} variable directly. It's being configured and not calculated. To Extract the username you could take a look into /etc/passwd file, but this is very system dependent, e.g. sometimes you have to look into a LDAP directory or the entries are propagated through NIS ...

edited Apr 06 '14 at 23:20

user

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answered Oct 27 '09 at 09:25

dz.

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For those landing here because gnome-terminal dropped support for `logname`, this seems to work well `$(logname 2>/dev/null || echo $SUDO_USER)`. Tested on MacOS too. Bug report: https://bugzilla.gnome.org/show_bug.cgi?id=747046 – tresf Nov 14 '16 at 19:35
logname 2>/dev/null || echo $SUDO_USER , command worked for me in the OS Ubuntu 16.04.6 LTS and Ubuntu 20.04 LTS. – Syed Faraz Umar Jun 05 '20 at 09:42

score 28 · Answer 2 · answered Feb 12 '15 at 13:38

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You can use $(logname), which returns your login name even if you are currently sudoing.

answered Feb 12 '15 at 13:38

Gauthier

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@Knetic for future you and other Googlers, it may not: https://bugzilla.gnome.org/show_bug.cgi?id=747046 – muru Feb 27 '17 at 13:52
It is returning sudo name on Ubuntu 16.04.1 LTS – Adnan Oct 16 '17 at 21:22
On Arch Linux I suggest using `echo $LOGNAME`... But it depends on your environment variables – NerdOfCode Feb 17 '18 at 20:32

brianegge · Answer 3 · 2009-10-27T11:31:25.023

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Inspect the variable SUDO_USER.

http://www.gratisoft.us/sudo/man/sudo.html#environment

Another way to get the user is via the who command. This is useful sometimes when you don't care if the user has sudo'd or not.

who -m | awk '{print $1;}'

edited Oct 27 '09 at 11:31

answered Oct 27 '09 at 09:27

brianegge

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score 9 · Answer 4 · answered Nov 02 '12 at 05:14

SUDO_USER isn't portable. It's unset on Fedora 17.

The $USER and $UID variables aren't predictable when invoking sudo either. Some distros report the sudoer, others report the root user.

It's by no means perfect, but you could use test -w ~root && echo I have write access to ~root.

Getting $USER inside shell script when running with sudo?

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